Most foolproof chemistry for cold weather use?

Batteries, Chargers, and Battery Management Systems.
Post Reply
maanebedotten   100 W

100 W
Posts: 112
Joined: Aug 31 2012 1:51pm
Location: A deserted island off the western coast of Norway

Most foolproof chemistry for cold weather use?

Post by maanebedotten » Jul 17 2020 7:29am

A friend wants me to build a bike. He is the kind of person that will find a way to break anything that is not completely foolproof and wants to use the bike year-round which means temps below -10c.

Is lifepo4 the right chemistry to go for in this case? If so, what cells are good these days? Headway? A123?

User avatar
amberwolf   100 GW

100 GW
Posts: 30787
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Most foolproof chemistry for cold weather use?

Post by amberwolf » Jul 17 2020 4:22pm

I'm not certain, but I think at those temps you'll need some way to heat the cells before charging them, regardless of chemistry, presuming the battery will be built onto the bike and not taken inside whenever not actually being ridden at that moment.

During riding, the actual riding will warm them up some, though at those temps they'll all sag a lot in voltage, and not have nearly the power output they would under "normal" conditions. To prevent that, you'd need to heat them up first to something like normal room temperatures.

So your best bet to have a well-performing pack under those conditions is probably to use whichever chemistry you feel best for the system for whatever other reasons, and then setup a heating system that is connected to the charger's AC input. Then build the charger into the bike, with a temperature control so the sensors inside the battery pack prevent the charger from being able to charge the batteries until they are at the right temperature range for charging at the rate the charger is set to. If theres a chance it could overheat the pack, you would add thermal breakers in the power line to the heaters, built into the pack itself, so that they break the connection before it's too hot, then reconnect when it cools down.


So you plug it in, and it heats it up (whcih will take a while, probably several hours, at those temepratures, as you don't want really hot heaters, just enough to keep it all warm), then charges them and the heaters stay on all the time it's plugged in, keeping it ready to ride.

If the pack is well-insulated, it'll stay warm thru the whole ride.

User avatar
TorgueRPM   100 mW

100 mW
Posts: 46
Joined: Jan 09 2019 3:27pm
Location: Milwaukee, Wisconsin, USA

Re: Most foolproof chemistry for cold weather use?

Post by TorgueRPM » Jul 17 2020 8:49pm

Lithium titanate supposedly works pretty well at low temperatures, but the energy density is only ~2 better than lead acid. Great discharge capability and can charge at 6C (at least Toshiba SCiB). Kind of a trade off.

User avatar
amberwolf   100 GW

100 GW
Posts: 30787
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Most foolproof chemistry for cold weather use?

Post by amberwolf » Jul 17 2020 11:21pm

Other chemistries also have an "operating range" down to the temperature range the OP needs, but they will sag in voltage a lot at those temperatures, compared to normal room temperatures...I don't know but suspect the same is true of LiTi / LTO as well. That's why I recommended the heaters--they may not be necessary, but they'll make a more foolproof "plug and play" pack, if setup right.

maanebedotten   100 W

100 W
Posts: 112
Joined: Aug 31 2012 1:51pm
Location: A deserted island off the western coast of Norway

Re: Most foolproof chemistry for cold weather use?

Post by maanebedotten » Jul 18 2020 6:51am

Charging will not be done below 0c. He just moved to a new apartment complex, so we do not yet know what temps the parking garage will see during winter, or even if he will have access to an outlet for charging at all in the garage. I assume most rides will start with battery above freezing temps, but since he will often go somewhere, park outside and stay for some hours before going home, the battery needs to be able to operate cold without damage.

I realize the performance will drop in low temps. My experience is that this is less of a problem than one might think because low temps usually come with slippery road surface so less power just makes it easier to keep the wheel from doing unintentional burnouts :D

I used to live close to where he lives when I built my first ebike, and went with a lifepo pack from ping since that was considered the safest chemistry and also was more tolerant to low temps than other chems available at the time. I ran that pack year round for 3 years before it was stolen. It did lose a little capacity over that time, and sagged a lot in the cold, but overall I was very happy with the pack. I am sure I would have gotten 5+ years out of it if it was not stolen.

I do not want to rely on heater as that adds complexity and points of failure.

maanebedotten   100 W

100 W
Posts: 112
Joined: Aug 31 2012 1:51pm
Location: A deserted island off the western coast of Norway

Re: Most foolproof chemistry for cold weather use?

Post by maanebedotten » Jul 18 2020 7:24am

After reading specsheets for the mj1 and 30q cells, it seems they are actually specced to operate down to -20c. My google-fu is not strong enough to find any discharge tests at low temps though. I have some of these cells on hand, but did not think they were an option for low temps. They are not as unlikely to produce fireworks as lifepo4 though.

Lithium-titanate seems very interesting. Are cells available to consumers at reasonable prices anywhere?

User avatar
fechter   100 GW

100 GW
Posts: 14986
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Re: Most foolproof chemistry for cold weather use?

Post by fechter » Jul 18 2020 11:23am

A123 are pretty good for cold temps but all battery chemistries will have reduced capacity when cold.
"One test is worth a thousand opinions"

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 18 2020 11:46am

LTO aka lithium-titanate Li4Ti5O12 for googling

Horrible energy density (better than lead but still)

But 50° below no problem.

Odd per-cell voltages, 5S per "12V" nominal.

Can routinely charge at 6C without hurting longevity - under 10min to Full!

Which is 10,000 cycles.

Also no problem running down to very low voltages.

Toshiba SCiB are the ones to look for, sometimes NOS shows up by the pallet.


Last edited by john61ct on Jul 18 2020 11:46am, edited 1 time in total.

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 18 2020 11:49am

LFP the charge rate needs to be drastically curtailed as you approach even 10°C

I would not charge at all near freezing

Winston / Thundersky claimed lower OK with their Yttrium doping but I've never seen it verified, everyone is skeptical of Mr Chung Hing Ka 

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 18 2020 11:51am

Operating, as in discharging is safe at the lower end of the spec'd ranges

but very inefficient.

It's charging too fast too cold that can render your investment scrap in one session.

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 18 2020 11:53am

Make the pack removable, bring it inside overnight

use any chemistry you like

999zip999   100 GW

100 GW
Posts: 9699
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: Most foolproof chemistry for cold weather use?

Post by 999zip999 » Jul 18 2020 2:31pm

Lots of LTO cells and pack builds here and. These people sell BMW LTO modules and A123 they get in and sell out quick. And are USA.https://batteryhookup.com/
Last edited by 999zip999 on Jul 18 2020 3:44pm, edited 1 time in total.

goatman   10 MW

10 MW
Posts: 2149
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: Most foolproof chemistry for cold weather use?

Post by goatman » Jul 18 2020 3:17pm

heres a thread

viewtopic.php?f=14&t=102387&p=1508261&h ... r#p1507609

i run my 25r at -5 and colder

User avatar
LeftieBiker   10 kW

10 kW
Posts: 930
Joined: Nov 06 2012 1:33am
Location: Upstate NY, United States

Re: Most foolproof chemistry for cold weather use?

Post by LeftieBiker » Jul 18 2020 3:32pm

Given the limitations above, it makes the most sense to build an easily removable pack, and just store and charge it inside. Charging right before a ride is best, so the risk involved is minimal, especially with LiFePo4.

kcuf   100 W

100 W
Posts: 219
Joined: Sep 29 2018 3:21pm

Re: Most foolproof chemistry for cold weather use?

Post by kcuf » Jul 18 2020 3:36pm

short range under brutal cold

si02 may be worth consideration

comparable bulk weight to pb

however much higher charge rate

plus excellent cold temp performance

non-balance as well

extremely stable safe long lasting
In 2013 an ad appears on Russia social networks: Интернет-операторы хотели! Работа в шикарном офисе в Ольгино !!!, зарплата 25960 рублей в месяц

goatman   10 MW

10 MW
Posts: 2149
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: Most foolproof chemistry for cold weather use?

Post by goatman » Jul 18 2020 4:05pm

LeftieBiker wrote:
Jul 18 2020 3:32pm
Given the limitations above, it makes the most sense to build an easily removable pack, and just store and charge it inside. Charging right before a ride is best, so the risk involved is minimal, especially with LiFePo4.
im kind of finding that charging a battery about 5 minutes right after using it is better if its warmer than room temperature.

im in a cooler climate so i should say it this way. if my pack temp is 80f/85f it takes a better charge than at room temperature, say 20 celsius/68f it doesnt take a charge as well

need to do some math to figure out amps required than size of battery and pick the battery by its resistance so it can self heat itself in cold weather is my opinion.

my 25r come inside at night in the winter and get charged right away. in the morning i put them on the bike, go to work and they sit outside in freezing temps all day and then i just go easy on the throttle for the first 10 minutes on the way home to let them warm up.

User avatar
LeftieBiker   10 kW

10 kW
Posts: 930
Joined: Nov 06 2012 1:33am
Location: Upstate NY, United States

Re: Most foolproof chemistry for cold weather use?

Post by LeftieBiker » Jul 18 2020 5:16pm

Generally speaking, it's better to charge right before riding because sitting at a high SOC isn't good for lithium chemistries. I'm not sure what Goatman means by 'doesn't take a charge as well' but most packs will happily charge at room temp, and room temp is better for their longevity than are higher temps.

goatman   10 MW

10 MW
Posts: 2149
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: Most foolproof chemistry for cold weather use?

Post by goatman » Jul 18 2020 7:55pm

battery will take in more capacity when its warmer, kinda sucks at room temperature and when life cycling it effects its lifecycle

maanebedotten   100 W

100 W
Posts: 112
Joined: Aug 31 2012 1:51pm
Location: A deserted island off the western coast of Norway

Re: Most foolproof chemistry for cold weather use?

Post by maanebedotten » Jul 19 2020 7:08am

Thanks for all the input guys! I am quickly catching up on battery tech thanks to your comments.

I am very tempted to just just build a pack with 30q cells, get a programmable bms and configure it conservatively with regard to both discharge current and voltage cutoffs.The guy who will be using it has severe adhd so he just does not have the attention required to be able to properly take care of a battery like most of us here would. He will probably forget he has a battery on charge and leave it for long periods of time connected to the charger. Then he will run full throttle until the bike stops and leave the battery empty for a long time until he eventually remembers to charge it.

Considering the abuse this pack will be subject to, I am however still worried about the safety aspect, so still leaning towards lifepo4. LTO and SiO2 seem interesting so I will read up on them, but availability might become a hurdle.

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 19 2020 8:36am

Someone like that should just own commercially produced products, or go without, unless silly wealthy.

DIY systems to protect the pack from owner abuse complicates things too much, in itself reducing reliability.

IMHO

maanebedotten   100 W

100 W
Posts: 112
Joined: Aug 31 2012 1:51pm
Location: A deserted island off the western coast of Norway

Re: Most foolproof chemistry for cold weather use?

Post by maanebedotten » Jul 19 2020 9:38am

At first
john61ct wrote:
Jul 19 2020 8:36am
Someone like that should just own commercially produced products, or go without, unless silly wealthy.
Agreed. Unfortunately no realistic commercial option exists.
john61ct wrote:
Jul 19 2020 8:36am
DIY systems to protect the pack from owner abuse complicates things too much, in itself reducing reliability.
It does not have to be more complicated or less reliable. With a programmable bms it is possible to play around with different values to increase lifespan of battery. Take the 30q cell as an example. By charging to 4.0v and discharging to 3.2v you still get about 2ah capacity depending on discharge current. In exchange you get increased cycle-life. Sitting for extended periods of time at 4v or 3.2v is of course not optimal, but much less degradation will occur than at 4.2v or 2.5v. I believe I can make a pack that will last 3 years or more, even with the abuse this guy will put on the pack. I might be wrong though, but in any case the pack should last him considerably longer than any readily available commercial one.

john61ct   100 GW

100 GW
Posts: 6290
Joined: Dec 18 2018 2:06pm

Re: Most foolproof chemistry for cold weather use?

Post by john61ct » Jul 19 2020 2:03pm

Yes I suppose. I would not go to that much trouble to accommodate that sort of disability myself

unless as I said if they were wealthy paying me heaps

or for my own kin.

leffex   1 kW

1 kW
Posts: 304
Joined: Apr 08 2012 4:39pm
Location: Sweden

Re: Most foolproof chemistry for cold weather use?

Post by leffex » Jul 20 2020 7:12pm

LTO or A123 that is a hardcore type of lifepo4 which is by weight and size /2 that of lead acid.

If you want A123 32113 cells I have a few if you want for free to pick up in Gothenburg Sweden, 5 minutes walk from train central area.

Samsung 29e 32e, LG mh1 mj1 or panasonic pf or ga. is even more capacity and lower weight than above specs.

Try to plan your battery size first. How many series and parallel? A 36v ebike battery is 10s4p usually making it fully charged 42v and 10ah in general. There's a choice if you have a smal battery. When you go much larger you can even use lower performance cells.
Salestech in an ebike store

John in CR   100 GW

100 GW
Posts: 14637
Joined: May 20 2008 12:58am
Location: Paradise

Re: Most foolproof chemistry for cold weather use?

Post by John in CR » Jul 21 2020 5:47pm

Keep the ebike inside in reasonable temps, not a freezing garage. Charge only while he can monitor it, since it's indoors. Then install the pack in a manner so that it's well insulated, so the inherent heat created during discharge keeps it warm enough to obtain full capacity. When weather is warmer, remove insulation a give it ventilation, though if the pack is of sufficiently low resistance the battery may not create enough heat to warrant special treatment to dissipate heat during the summer.

999zip999   100 GW

100 GW
Posts: 9699
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: Most foolproof chemistry for cold weather use?

Post by 999zip999 » Jul 21 2020 9:02pm

What motor and controller are you going to run as this makes a difference how much of a demand you put on your battery I always over built I have a 180 amp battery that I went to use at 90 amps.

Post Reply